There is interest in the manufacture of brake rotors that are vented for cooling and contain sound damping inserts. Such rotors are often used for braking of vehicle wheels.
In many embodiments such brake rotors have a round hub for attachment to a vehicle wheel and a radially outwardly extending rotor portion attached to the central hub. In vehicle operation the hub and rotor rotate about a central axis coincident with the rotational axis of the wheel to which they are attached. The rotor is shaped like an annular disk with an annular body, extending radially from the hub, that has two flat, parallel, annular faces (sometimes called “cheeks”) and a circumferential end surface. One cheek of the rotor is on the hub side of the brake rotor structure and the other cheek is the rotor surface on the opposite side of the rotor body. In a braking operation, pads of friction material are pressed tightly against the then rotating cheeks of the rotor to stop rotation of the rotor and attached wheel. Such braking friction produces heat in the rotor and mechanical vibrations. Sometimes the vibrations result in high frequency noise (typically brake squeal).
In some rotor designs the rotor body is solid, but in many rotors the body portion contains several generally radially extending, transverse vanes defining intervening air ducts for air cooling of frictional heat produced in the rotor body during braking. The vanes are formed generally centrally of the rotor body to leave one or two outboard durable body thicknesses for braking pressure applied against the cheek surfaces. In order to suppress brake squeal it is desired to provide an annular, typically flat insert piece in one or both rotor body portions outboard of the vanes. It is also desired to cast rotor material around the noise damping insert body so as to form suitable noise damping (typically by coulomb friction damping) surface regions between contiguous faces of the enclosing cast rotor metal and the insert material.
By way of example and as an illustration, annular insert plates may be steel stampings, with or without a coating of particulate material, for frictional contact with the engaging inner face surfaces of the cast rotor material. And the rotor and hub may be formed of a suitable cast iron composition.
It has been a challenge to devise a practical and economical method of manufacturing such noise damped, vented brake rotors with vanes for cooling and inserts for vibration damping. This specification provides an assembly of cores, typically three specially designed and complementary resin-bonded sand cores, that enables sand casting of pairs of such rotors. An assembly of cores is also provided that enables sand casting of more than two rotors at the same time.